Re: [PATCH v2 1/2] dt-binding: clock: cs2600: Add support for the CS2600

[Richard Fitzgerald <rf@opensource.cirrus.com>]

On 19/12/24 13:16, Krzysztof Kozlowski wrote:
> On 19/12/2024 13:59, Charles Keepax wrote:
>> On Thu, Dec 19, 2024 at 12:39:38PM +0100, Krzysztof Kozlowski wrote:
>>> On 19/12/2024 12:02, Charles Keepax wrote:
>>>> On Thu, Dec 19, 2024 at 09:51:00AM +0100, Krzysztof Kozlowski wrote:
>>>>> On Wed, Dec 18, 2024 at 08:46:30PM -0600, Paul Handrigan wrote:
>>>>>> +/* CS2600 Auxiliary Output */
>>>>>> +#define CS2600_AUX_OUTPUT_FREQ_UNLOCK	0
>>>>>> +#define CS2600_AUX_OUTPUT_PHASE_UNLOCK	1
>>>>>> +#define CS2600_AUX_OUTPUT_NO_CLKIN	2
>>>>>
>>>>> I still don't see why these three are supposed to be bindings. Drop
>>>>> them.
>>>>
>>>> In a binding one would presumably do:
>>>>
>>>> cirrus,aux-output-source = <CS2600_AUX_OUTPUT_FREQ_UNLOCK>;
>>>>
>>>> Apologies but I don't quite understand what you mean by the values
>>>> are not used in the binding? The driver reads the property and sets
>>>
>>> There is no user of these defines, so not a binding.
>>>
>>>> the pin to have the appropriate function. Admittedly one could drop
>>>
>>> It's not a proof that this is a binding.
>>>
>>>> the defines and then DTS would just have to do:
>>>>
>>>> cirrus,aux-output-source = <0>;
>>>>
>>>> But that feels a bit less helpful when reading the binding.
>>>
>>> Binding and being helpful are two different things. This to be the
>>> binding, it has to be used as a binding, so some translation layer
>>> between driver and DTS. It must have an user in DTS. I keep repeating
>>> this over and over...
>>>
>>
>> Apologies, but I not sure I totally follow this, and apologies if
>> you have already explained this are there some docs I can look
>> at?
>>
>> I think you are saying because these defines merely represent the
>> valid values for a device tree property and are not translated
>> into different values you can't put defines for them in the binding
>> header?
>>
>> So this would not be allowed:
>>
>>    #define CS2600_AUX_OUTPUT_FREQ_UNLOCK 0
>>
>>    cirrus,aux-output-source = <CS2600_AUX_OUTPUT_FREQ_UNLOCK>;
>>
>>    device_property_read_u32(dev, "cirrus,aux-output-source", &val);
>>    regmap_write(regmap, CS2600_OUTPUT_CFG2, val);
>>
>> But this would be fine:
>>
>>    #define CS2600_AUX_OUTPUT_FREQ_UNLOCK 1
>>
>>    cirrus,aux-output-source = <CS2600_AUX_OUTPUT_FREQ_UNLOCK>;
>>
>>    device_property_read_u32(dev, "cirrus,aux-output-source", &val);
>>    switch (val) {
>>    case CS2600_AUX_OUTPUT_FREQ_UNLOCK:
>>      regmap_write(regmap, CS2600_OUTPUT_CFG2, 0);
>>    }
>>
>> And this would also be fine?
>>
>>    cirrus,aux-output-source = <0>;
>>
>>    device_property_read_u32(dev, "cirrus,aux-output-source", &val);
>>    regmap_write(regmap, CS2600_OUTPUT_CFG2, val);
>>
> Yes. If you want to use in DTS user-readable values, then use string.
> 

I don't understand this. Why should we have to use a string value for
something that only needs a simple integer value? Why can't we define
constants with meaningful names?

> Best regards,
> Krzysztof